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Study Finds Sierra Nevada Glaciers Have Endured Since the Ice Age Yet Could Vanish This Century

Cosmogenic-isotope dating of rocks at four Yosemite-area glaciers indicates continuous cover that challenges earlier assumptions.

Repeat photography of Maclure Glacier in Yosemite National Park. September 1914 versus September 2021.
Clouds move over snow-covered mountains in the Eastern Sierra in March 2024. Some glaciers on the range date back to the Ice Age, a new study has found.
Maclure Glacier in Yosemite National Park. 

Overview

  • Published in Science Advances on Oct. 1, the study analyzed Conness, Maclure, Lyell and Palisade glaciers using in situ beryllium and carbon isotopes to reconstruct ice coverage.
  • Exposure ages show rocks beneath these ice masses were shielded for millennia with no full disappearances, though East Lyell was likely smaller in the early Holocene.
  • Researchers report many Sierra glaciers have already lost about 70% to 95% of their ice since the late 1800s based on observations and records.
  • California summers have warmed roughly 3.6°F (2°C) over preindustrial levels, consistent with rapid retreat and projections that many glaciers could vanish by 2100.
  • The loss of glacier meltwater would remove a late-season buffer that sustains streams, with some tributaries to the Tuolumne River expected to run dry at times.